She was rushed to hospital with head injuries and died three weeks later.
In an appeal against his conviction, Foley claimed he did not receive proper advice before pleading guilty and another neighbour, Mr T, who was also Lawrence's lover, was responsible for her death.
According to Foley - who admits to striking Lawrence twice with a garden gnome, but denies beating her with a jimmy bar - Mr T, who has name suppression, "seized the opportunity" after he had left her flat and finished her off before emergency services could arrive.
But a decision released by the Court of Appeal today said there were no grounds for Foley's claim.
"In our view no jury would have entertained a reasonable doubt as to Mr Foley's guilt by considering Mr T (or any other person) may have undertaken a second murderous attack on Ms Lawrence in the five minute timeframe available that night."
In sentencing, Justice Mander said Foley had "harboured some jealousy" after thinking she was having a relationship with another man.
Reports before the court during his trial noted Foley - who had 85 previous convictions primarily for fraud and dishonesty offences - had a "habit of telling grandiose lies".
In his appeal, Foley also claimed his ability to plead guilty was affected by his ill-health after going on a hunger strike in prison and being housed in a prison "at risk unit".
He also said he was denied the right to a fair trial as there was an abuse of power by prosecuting authorities.
The Court of Appeal decision said Foley had made a "free and informed" decision to enter his plea.
It also noted Foley hadn't suggested the existence of a second assailant until about nine months after her death.
"This is not a case where it can be said that evidence has been lost because of omissions by the police involving bad faith, or where the lost evidence would have been of real assistance to the defence."
